Salen-type zirconium complexes with a labile coordination site and a robust skeleton: crystal structure of [(t-Bu4-salen)ZrCl2(H2O)]

Treatment of LZrCl2 (L=N,N′-ethylenebis(3,5-di-tert-butylsalicylideneiminato) (1), N,N′-o-phenylenebis(3,5-di-tert-butylsalicylideneiminato) (2)), which is an effective catalyst precursor for ethylene oligomerization, with 1.5 equiv of water in toluene afforded H2O-coordinating salen-type zirconium complexes [LZrCl2(H2O)]. The effects of the content of H2O and the temperature on the equilibrium of association and disassociation of H2O molecule in [LZrCl2(H2O)n] (n=0, 1) were studied in solution (CDCl3) by 1H NMR spectroscopy. The crystal and molecular structure of [1(H2O)] was determined by X-ray diffraction analysis, which revealed that a herringbone supramolecular assembly was constructed in the crystalline state of [1(H2O)], stacked by the intermolecular hydrogen bonds between the OH group of the coordinating H2O and one of the chloride ligands.